C# - Standard-Kontextmenü zu RichTextBox-Control hinzufügen

public static void ExtendWithContextMenu(this RichTextBox rtb)
{
    ContextMenuStrip ctx = new ContextMenuStrip();

    ToolStripMenuItem cut = new ToolStripMenuItem(
        "Ausschneiden", null, (sender, e) => rtb.Cut());
    
    ToolStripMenuItem copy = new ToolStripMenuItem(
        "Kopieren", null, (sender, e) => rtb.Copy());
    
    ToolStripMenuItem paste = new ToolStripMenuItem(
        "Einfügen", null, (sender, e) => rtb.Paste());

    ctx.Items.Add(cut);
    ctx.Items.Add(copy);
    ctx.Items.Add(paste);

    rtb.ContextMenuStrip = ctx;

    ctx.Opening += 
        (sender, e) =>
        {
            bool noSelectedText = string.IsNullOrEmpty(rtb.SelectedText);
            cut.Enabled = !noSelectedText;
            copy.Enabled = !noSelectedText;

            bool noClipboardText = string.IsNullOrEmpty(Clipboard.GetText());
            paste.Enabled = !noClipboardText;
        };
}